The invention relates generally to meltblowing methods and systems, and More particularly to parallel plate meltblowing die assemblies and meltblowing system configurations useable for precisely controlling the dispensing and uniform application of meltblown adhesive filaments onto moving substrates.
Meltblowing is a process of forming fibers or filaments by drawing and attenuating a first fluid flow with shear forces from adjacent relatively high velocity second fluid flows. Molten thermoplastic flows, for example, may be drawn and attenuated by heated air flows to form meltblown thermoplastic filaments. Generally, meltblown filaments may be continuous or discontinuous, and range in size between several tenths of a micron and several hundred microns depending on the meltblown material and application requirements. Early applications for meltblowing processes included the formation of non-woven fabrics from meltblown filaments drawn to vacillate chaotically.
More recently, meltblowing processes have been used to form meltblown adhesive filaments for bonding substrates in the production of a variety of bodily fluid absorbing hygienic articles like disposable diapers and incontinence pads, sanitary napkins, patient underlays, and surgical dressings. Many of these applications, however, require a relatively high degree of control over the dispensing and application of the meltblown filaments, particularly meltblown adhesives deposited onto substrates which are extremely temperature sensitive. But meltblown filaments drawn to vacillate chaotically are not generally suitable for these and other applications requiring increased control over the dispensing and application of the meltblown filaments.
The referenced copending U.S. application Ser. No. 08/717,080 filed Oct. 10, 1996 entitled xe2x80x9cMeltblowing Method and Apparatusxe2x80x9d incorporated by reference herein marked a significant advance in meltblowing technologies, and particularly for meltblowing applications requiring relatively precise control over the dispensing of individual meltblown filaments onto moving substrates. The referenced copending application is drawn generally to parallel plate die assemblies having a plurality of adhesive and air dispensing orifices arranged in a variety of spatial configurations for dispensing meltblown adhesives, and more particularly for relatively precisely controlling frequency and amplitude parameters of individual meltblown filaments to provide selective and uniform application of the filaments onto moving substrates.
The present invention is drawn to further advances in meltblowing technology, and is applicable to the dispensing of meltblown adhesive filaments onto moving substrates, especially in the production of bodily fluid absorbing hygienic articles.
It is thus an object of the invention to provide novel methods and systems for practicing meltblowing processes, and more particularly for applying meltblown adhesives onto moving substrates.
It is another object of the invention to provide novel methods and systems for practicing meltblowing processes by dispensing first and second fluids from corresponding first and second orifices of a die assembly to form second fluid flows along substantially opposing flanking sides of a first fluid flow, whereby the first fluid flow is drawn and attenuated to form a first fluid filament. A more general object of the invention is to dispense the first fluid from a plurality of first orifices and the second fluid from a plurality of second orifices to form a plurality of first and second fluid flows arranged in an array, whereby the plurality of first fluid flows are drawn and attenuated to form a plurality of first fluid filaments.
It is also an object of the invention to provide novel methods and meltblowing die assemblies for directing first and second fluid flows parallelly, or divergently, and it is another object of the invention to provide die assemblies for directing two second fluid flows convergently toward a common first fluid flow whereby the first fluid flow is directed parallelly or divergently relative to other first fluid flows. It is a related object of the invention to dispense first and second fluid flows having equal first fluid mass flow rates and equal second fluid mass flow rates to provide more uniform dispensing and control over the meltblown filaments.
It is a further object of the invention to provide novel methods and systems for practicing meltblowing processes by depositing first meltblown fluid filaments onto a moving substrate by vacillating the filaments non-parallel to a direction of substrate movement, and more generally depositing a plurality first fluid filaments onto a moving substrate by vacillating some of the plurality of first fluid filaments non-parallel and other filaments parallel to a direction of substrate movement. It is a related object of the invention to control vacillation parameters of a first fluid flow by an angle between the first fluid flow and one or more flanking second fluid flows, among other variables.
It is another object of the invention to provide novel methods and meltblowing die assemblies comprising a plurality of at least two parallel plates compressably retained between first and second end plates, and it is a related object of the invention to dispose a rivet member through an opening in the die assembly to retain the plurality of parallel plates in parallel relationship while the die assembly is compressably retained between the first and second end plates.
It is yet another object of the invention to provide novel methods and meltblowing die assemblies coupleable to an adapter or an intermediate adapter having a mounting surface with a central first fluid outlet and a second fluid outlet for supplying first and second fluids to the die assembly, whereby the die assembly may be oriented in one of two directions distinguished by 90 degrees by mounting the die assembly on either the adapter or intermediate adapter. It is a related object of the invention to rotatably couple the die assembly to the intermediate adapter or to rotatably couple the adapter to a nozzle module to permit rotational orientation of the die assembly relative thereto.
It is still another object of the invention to provide novel meltblowing methods and systems including meltblowing die assemblies coupled to a fluid metering device for supplying a first fluid thereto, and to couple one or more die assemblies to a main manifold having corresponding first fluid supply conduits for supplying a first fluid from the fluid metering device to the one or more die assemblies. It is another object of the invention to couple the die assemblies to the main manifold with a plurality of corresponding nozzle modules, whereby each nozzle module supplies first and second fluids to the corresponding die assembly. And it is an alternative object of the invention to interconnect the die assemblies to the main manifold with a common nozzle adapter plate, which supplies first and second fluids to each of the plurality of die assemblies.